Spark-plug.



H. HORN. SPARK PLUG. APPLICATION FILED JUNE I, 1918. x 1,290,559. Patnted Jan. 7,1919.

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SPARK-PLUG.

Specification of Letters Patent.

Patented J an. 7, 1919.

Application led J' une 1, 1918. Serial No. 237,681.

To a-ZZ'wLom t may concern: Be it known that I, HUGO HORN, a citizen of the United States, and resident of Milwaukee, in the county of Milwaukee and State of Wisconsin, have invented new and useful Improvements in Spark-Plugs, of which the followin is a description, reference being had to t e accompanying draw- .and

ings, which are a part of this specification.

This invention relates to improvements in spark plugs.

It is one of the lobjects of the present 1nvention to rovide a spark plug having a visible spark to indicate that the electrodes of the spark plug withim the combustion engine are properly performing their function.

A further object of the invention is to provide a spark plug articularly adapted for use ina plural cy inder engine to indicate, in case of trouble, the particular spark plug which is not properly igniting the charge of gas within the cylinder in which the spark plug is mounted.

A further object of the invention is to provide a spark plug having means for con veniently adjusting the resistance of the visible or auxiliary air gap to control the strength of the spark igniting the charge within the engine cylinder without removing the plug from the cylinder.

A further object of the invention is to provide a spark plug which is of simple construction, is strong and durable and is well ada ted for the purpose described.

ith the above andother objects in view the invention consists of the improved spark plu and its parts and combinations as set :Eori in the claims, and all equivalents thereof. A l

In the accompanying drawing in which the same reference characters indicate the same parts in all of the views;

Figure lis a side view of the improved spark plug shown on a large scale for convenience of illustration;

Fig. 2 is a vertical sectional view thereof;

Fig. 3 is a transverse sectional view taken on line 3-3 of Fig. 2.y

Referrin tothe drawing the numeral 5 indicates t e plug socket or sleeve which is formed with athreaded lower part 6 of an standard size and an enlar ed vupper part having hexagonal faces 8 w ich are engaged` by a wrench in threading the plug into an has a holding nut 22and a termin engine cylinder. The said upper part 7 has a bore of larger diameter than the lower part which forms an annular tapered shoulder 9 against which bears the medial annular tapered shoulder 10 of the insulating plug 1l.

The plug may be formed of porcelain, micar or other desirable insulating land heat resisting material and is formed with a lower portion 12, a medial enlargement 13, an upper shouldered part 14, and an upper extension 1 5 of less diameter than the shouldered portion 14.. rllhe tapered shoulder 10 isapproximately of the same angle as the shoulder 9 and a copper gasket 10 interposed between the two shoulders forms a gas-tight joint therebetween.

- A sight bushing 16 surrounding the insulating plug and threaded into the upper portion of the plug socket impinges against the upper surface of the medial enlargementA of the insulating plug and firmly clamps it in the socket and Aagainst the gasket. The` bushing is formed with sight openings 17 in its opposite sides and these openings are protected b a transparent tube 18,-, preferably glass, w ch is positioned within the bushing, and surrounds the insulating plug and is interposed between tleupper wall of the bushing and the medial enlargement and forms a spark chamber. A rubber gasket 19 interposed between the bushing and the upper edge of the glass tube holds said tube firmly in position and also permits the un-v equalexpansion of the glass tube and adjacent parts` without liability of breaking the parts.

A main electrode 20 formed of an desirable metal extends centrallyl longitudi nally through the insulating plug member 11 andprojects slightly from the lower end portion thereof. The upper end of the central electrode threads into a threaded extension 21 which projects upwardly from the upper end portion of the insulating plug and a clamping nut 23 threaded thereon.

The insulating lug 11 is also provided with an auxiliary e ectrode 24 which extends through one side portion of the insulating plug 11 in a line approximately parallel to the central'electrode. The lower end ortion 24 of the auxiliary electrode is `ent toward the lower end portion of the central electrode and terminates a slight distance therefrom to form a spark gap which is`jumped-by the current to ignite the comseen that the spark plu bustible charge of the 'engine towhich it is connected. l

rlhe upper end portion of the auxiliary electrode extends adjacent the upper surface of the shoulder part 14 of the insulating plug and is'provided with an enlargement or head 25 which projects above said shoulder and is visible through the sight openings 17.

An auxiliary sleeve 26 surrounding the insulating plug and threaded through the upper portion of the sight bushing 16 has its lower or inner annular edge portion 26 positioned adjacent the upper end portion of the enlargement or head 25 of the auxiliary electrode 24 to form an auxiliary or ground spark gap which intensities the spark at the main gap between the electrodes 20 and 24. The sleeve 26is'iif0r1ned with a milled annular flange 26 for conveniencein adjusting the distance between the electrodes forming the ground spark gap. An

extension and protecting sleeve 27 surrounds the upper end portion o the insulating plug and is interposed between the sleeve 26y and the nut 22.

ln use the spark plug is mounted on an engine and connected to the ignition electric circuit in the usual manner and when operating in proper manner the auxiliary spark is visiblethrough the sight openings of the sight bushing thus enabling the user to easily determine if any of the cylinders of the engine miss firing. rlhe auxiliary spark gap also intensifies the spark of the main gap, which tends to increase the etheiency of the combustible charge and also tends to prevent carbon deposits forming on the electrodes at the spark gaps.-

From the foregoing description it will be is of very simple construction and is we l adapted for the purpose described. Y

What Iclaim as my invention is:

l. A spark plug, comprising a plug socket having a threaded lower part, a sight bushing threaded on the plug socket, an insulating plug member extending into the plug socket and through the sight bushing, a main electrode extending through the insulating plug, an auxiliary electrode extending through a portion of the insulating plugand having its lower end terminating adjacent the lower end portion of the main electrode to form a main spark gap therebetween,

and a sleeve threaded into the bushing and extending adjacent the upper end portion of the auxiliary electrode to form an auxiliary spark gap and ground connection'therebetween.

2. A spark plug, comprising a plug'socket having a threaded lower part and an enlarged upper part forming an inner shoulder, an insulating plug member extending into the plug socket and having a medial en- Landes@ largement which bears against the inner shoulder, 'a bushing threaded into the enlarged upper -part of the plug socket and bearing against the enlargement of the insulating plug, said 'bushing having a sight opening, a main electrode extending longi` opening, and a terminal connection means atk the upper end of the main electrode.

3. A spark plug, comprising a plug socket having a threaded-lower part and an enlarged upper part tormi'ggazan inner shoulder, an insulating plug memb'erextending into the plug socket and having av I Iledia'll enlargement which bears against the inner shoulder, a bushing threaded into the enlarged upper part of the plug socket and bearing against the enlargement of the insulating plug, said bushing'having a sight opening, a main electrode extending longitudinally through the insulating plug, an auxiliary electrode extending through a portion of the insulating plu and having its lower end terminating adjacent the lower end portion of the main electrode to form a main spark gap therebetween, an electrode sleeve threadedinto the bushing and extending adjacent the upper end portion of the auxiliary electrode to form an auxiliary spark gap and ground connection therebetween Which is visible through the sight opening, an extension sleeve surrounding the upper ortion of the insulating plug member an bearin against the electrode sleeve,`a nut threade on the main electrode' and bearing against the extension sleeve, and a terminal connection means at the upper end of the main electrode.

4. A spark plug, comprisinga metal plug socket having a spark chamber in its upper end portion, an insulating'member extending socket having a threaded lower end portion and a spark chamber in its upper end portion, an insulating member extendino` through the threaded portion and the spark chamber, a main electrode extending through the insulating member, an auxiliary electrode extendin through a portion of the insulating mem er and having one of its end portions terminatin adjacent the lower end of the main electro e andy its other end terminating within the spark chamber, lsaid spark chamberformed in part of a bushing having a sight opening,\a sleeve surrounding the insulating member and threaded into the bushing and having its `\,inner edge portion positioned adjacent the end of the auxiliary electrode within the chamber to form an auxiliary and ground spark gap therebetween, anda terminal connection means on the upper end portion of the main electrode.

6. A spark plug, comprising a plug socket having a threaded lower part and an enlarged upper part provided with an internal thread, said enlargement forming an inner shoulder, an insulating plug member extending into the plug socket and having a medial enlargement which bears against the socket shoulder, said insulating plug also havin a shouldered portion, a bushing,` threa ed into the plug socket and bearing ber, and in part formina spark chamber, a v

main electrode exten ng longitudinally through the insulating plug member, an auxiliary electrode extending through a portion of the insulating plug member and having its lower end bent at an angle and terminating adjacent the main electrode to form a main spark gap therebetween, the upper end of the auxiliary electrode having an enlargement which terminates in the spark chamber, an electrode sleeve threaded into the plug member and surrounding the insulating plug member and having its inner edge portion positioned adjacent the end of the auxiliary electrode within the chamber to form an adjustable auxiliary and ground spark gap therebetween, an extension sleeve bearing against the sleeve electrode, a nut threaded on the upper end of the main electrode and bearin against the extension sleeve, and a terminal nut threaded on the upper end of the main electrode.

In testimony whereof, I aflix my signature.

HUGo HORN. 

